We download boot.iso first, and add kickstart file into it
recreate a new iso file named custom.iso. We can not tell it is
rhel6u1 or rhel6u2 from the custom.iso, so remove it before
creating a new one.

I mean why not change the utils/ksiso.sh to accept a argument,
and create the custom.iso in the desired target dir, such as
/var/cache/libvirt-test-API/$guest/

We can do that, if that is a better way.
Currently, we keep all of this stuff in local folder for debugging
or checking.

If we have good reason to move the folder to
/var/cache/libvirt-test-API

it's ok for me.

Every time we install a new guest, we create a folder named after the

name of the guest in root of libvirt-test-API. All of the related
temporary
files will be generated in this folder. The custom.iso is created in
this

folder.

I mean throw all of these stuffs into /var/cache/libvirt-test-API/$guest.